1. Call customer care and ask them to upgrade your card to Pinnacle without paying the joining fee. There is 90% chance that they will decline your request. Then told him/her to raise your request to his/her senior. If they reject your request then wait for 2 days and then raise request again. If you have moderate spending they will surely accept your request after 2-3 rejections.
2. If you don't want to call again and again then email to '
head.cardservices@indusind.com' to upgrade your card without paying the Joining Fee and also mention you don't need Joining benefits. Escalate to Principal Nodal Officer if they reject.
You have to be patient to deal with them.